Many types of mining equipment have been proposed for mining coal and other minerals economically and expeditiously. The coal is normally cut-out of a solid vein and dropped on a conveyor to load the coal in a shuttle car or the like for transport to a remote location for processing. One type of such mining equipment has cutters mounted on rotating arms which are, in turn, mounted on a mobile vehicle which must be steered to place the cutters in position for cutting purposes.
Another type of mining equipment comprises a horizontally disposed auger adapted to remove soft coal in lumps with minimum fine breakage. The cuttings are carried backwardly by the auger flights to a conveyor belt or the like for loading purposes. The auger is used for mining coal from the edges of strip pits with the standard practice being to cut parallel holes, thus leaving thin pillars or ribs between the holes to support the overburden. Alternatively, a single hole may be cut from a centerline tunnel and the coal from each side thereof being thereafter drilled and blasted into it for recovery purposes.
One of the problems with such drilling equipment is the inability to recover a maximum amount of coal due to the cylindrical bores which are formed thereby. In addition, when the drill is lengthened up to 200 feet, for example, the auger will tend to "wander" and thus cause binding and related problems. Also, the auger itself is not always capable of penetrating obstructions, such as a hard rock seam or a bolder, and thus requires exotic tips on the auger or dynamiting to complete the coal recovery operation.